Generally, in the semiconductor industry the most difficulty and/or problems occur with the formation of external electrical connections and with interconnections to different components on a single substrate. Semiconductor devices are typically fabricated on a planar substrate by sequentially growing or depositing several different layers of material and then patterning or etching one or more of the layers to expose a lower surface. Metal is then deposited on the exposed surfaces for interconnections or external connections.
One problem in this process is that the etching requires masking which adds several complicated steps to the process and, consequently, a large amount of labor and cost. Also, the metal contacts require a relatively large amount of real estate and, consequently, many semiconductor devices are limited in size by the ability to provide external connections to them.
A device which solves some of these problems is disclosed in a application entitled "Ultra-Small Semiconductor Devices and Methods of Fabricating and Contacting", Filed Mar. 7, 1995, bearing Ser. No. 08/399,809, and assigned to the same assignee now U.S. Pat. No. 5,659,179. In a specific embodiment, devices of this type are fabricated by providing a supporting substrate with a planar surface and patterning the planar surface of the substrate to form a first pattern edge with a side wall. A layer of material is conformally formed over the substrate surface, including the side wall of the first pattern edge and anisotropically removed so as to leave a selected thickness of the layer of material covering the side wall. The surface of the substrate is etched to form a second pattern edge laterally spaced the selected thickness from the first pattern edge by using the selected thickness of the layer of material covering the side wall as a mask. The selected thickness of the layer of material covering the side wall is then removed and a plurality of overlying layers of material are consecutively formed, at least partially defining a semiconductor device, in overlying relationship to first and second opposite sides of each of the first and second pattern edges so that discontinuities are produced in the layers at each of the first and second pattern edges and a first layer of the plurality of layers on the first opposite side of the first pattern edge is aligned with and in electrical contact with a second layer of the plurality of layers on the second opposite side of the first pattern edge and a third layer of the plurality of layers on the first opposite side of the second pattern edge is aligned with and in electrical contact with a fourth layer of the plurality of layers on the second opposite side of the second pattern edge.
However, these devices still require some additional growth steps which add to the fabrication method.
Accordingly, it would be highly advantageous to provide semiconductor devices and methods of manufacture which do not include additional growth steps for the formation of interconnections and external connections and which utilize conventional lithography.
It is a purpose of the present invention to provide novel methods of fabrication and connection for ultra-small semiconductor devices.
It is another purpose of the present invention to provide novel methods of fabrication and connection of ultra-small semiconductor devices in which at least some of the interconnections are formed automatically during the formation of the various layers.
It is still another purpose of the present invention to provide novel methods of fabrication and connection of ultra-small semiconductor devices in which external terminals and interconnections are formed without requiring additional growth steps.
It is a further purpose of the present invention to provide novel methods of fabricating ultra-small semiconductor devices which are smaller than previously possible with standard external terminals.
It is still a further purpose of the present invention to provide novel simplified methods of fabrication and connection of ultra-small semiconductor devices.